Proverbs 15:13 - The Popular Commentary by Paul E. Kretzmann

v. 13. A merry heart maketh a cheerful countenance, for when the spirit is joyous, it brightens the face; but by sorrow of the heart the spirit is broken, if grief has taken possession of the heart, the powers of the mind are also influenced, clearness of thought is gone, and the shock proves generally disastrous to the whole spiritual life.